代码语言：javascript复制
// keyBy
function keyBy(list, by) {
return list.reduce((acc, x) => {
acc[by(x)] = x;
return acc;
}, {});
}
console.log(
keyBy(
[
{ id: 1, name: "beilei" },
{ id: 2, name: "xinqing" },
],
(x) => x.id
)
);
// maxBy
const maxByData = [{ value: 6 }, { value: 2 }, { value: 4 }];
function maxBy(list, keyBy) {
return list.reduce((x, y) => {
return keyBy(x) > keyBy(y) ? x : y;
});
}
console.log(maxBy(maxByData, (x) => x.value));
// maxBy 返回数组，可能有多个符合条件的对象
function maxByArr(list, keyBy) {
return list.reduce(
(acc, x) => {
if (keyBy(x) > keyBy(acc[0])) {
return [x];
}
if (keyBy(x) === keyBy(acc[0])) {
return [...acc, x];
}
return acc;
},
[list[0]]
);
}
console.log(maxByArr(maxByData, (x) => x.value));参考链接：https://github.com/shfshanyue/Daily-Question/issues/646
